Analyze the Data Chapter 4: FACS of Glucose Transport In unstimulated muscle cel
ID: 196186 • Letter: A
Question
Analyze the Data Chapter 4: FACS of Glucose Transport
In unstimulated muscle cells, the glucose transporter Glut4 is present in the membrane of endosomes. Upon stimulation of these cells with insulin, the endosomes fuse with the plasma membrane, thereby depositing Glut4 in the plasma membrane, where it serves to transport glucose into the cells (see Figure 15-34 on page 659). In order for insulin to elicit this change in Glut4 localization, insulin must bind to its receptor, present in the plasma membrane of some cells. To determine if a stem cell line can be induced in culture to differentiate into muscle cells in which Glut4 is expressed and exhibits this insulin-dependent change in behavior, the following studies were undertaken.
A stem cell line was incubated under culture conditions in which stem cells can differentiate into various specific cell types. The cells were then incubated in the presence and absence of insulin. To determine if either Glut4 or the insulin receptor were present on the cell surface of cells within this population, antibodies that specifically recognize each protein were used to label the cells. Glut4 on the cell surface was detected by an anti-Glut4 antibody, which fluoresces green; the insulin receptor on the cell surface was detected by an anti-insulin receptor antibody, which fluoresces red. These cells were then placed in a fluorescence activated cell sorter FACS machine (see Figure 9-29 in the text) and sorted based on both red and green fluorescence. The following data were obtained. Each • on the graphs represents 20 cells. An increased value of fluorescence intensity indicates that more antibody has bound to those cells.
Do any cells in the population express Glut4 on their surface? Is this expression dependent
on the presence of insulin receptor? Is this expression dependent on the presence of insulin?
Explain.
(a) Insulin (b) Insulin 10 10 0 104 100 10 104 Red fluorescence 10 10 Red fluorescenceExplanation / Answer
Cells which express GLUT shows green fluorescence. As we can see from both the graph that only in the b figure there are cells which express GLUT4.
The GLUT4 expression is independent of the expression of the insulin receptor. As we can see from A graph that even though cells were expressing Insulin receptors there was no fluorescence fro GLUT4 receptors
The GLUT4 expression is dependent on the presence of insulin. When insulin was added in the media cells started expressing GLUT4 receptor which can be seen in graph B where cells starts showing green fluorescence durign FACS
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